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Healthy Animals Fall 22 > Neuro opthalmology/vision path > Flashcards

Neuro opthalmology/vision path Flashcards

1
Q

What innervates the globe and adnexa?

A

CN 2-8 and 10
ANS

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2
Q

What is cranial nerve 2?

A

optic nerve
made of retinal ganglion
axons exit at optic disk
cross over at optic chiasm
optic tracts then to brain

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3
Q

What does a lesion of CN 2 cause?

A

blindness
dilated pupils
absent PLR

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4
Q

What is CN 3?

A

oculomotor nerve
inervates levator palpebrae superioris muscle (lifts eyelid)
provides motor fibers to all muscles except a few

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5
Q

What muscles aren’t innervated by CN3?

A

LR6SO3
Lateral rectus (6)
Retractor bulbi (6)
superior/dorsal oblique (4)

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6
Q

What do lesions of CN 3 cause?

A

dilated pupil
ventral lateral strabismus (down and out)
Ophthalmoplegia
ptosis

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7
Q

What is cranial nerve 4?

A

trochlear nerve
innervates superior oblique
rare to have as isolated lesion
normally rotates dorsal globe medially
leasion causes extorsion (dorsal globe goes laterally)

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8
Q

What is CN 5?

A

trigeminal nerve
3 branches

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9
Q

What is the first branch of the trigeminal nerve?

A

ophthalmic
sensory fibers from cornea, conjunctiva, superior lid
afferent arm of oculocardiac reflex
lesions cause loss of sensation and decreased reflex tear production

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10
Q

What is the second branch of CN 5?

A

maxillary branch
sensory to skin of lower lid
lesion causes loss of sensation

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11
Q

What is the third branch of CN 5?

A

mandibular
motor to muscles of mastication
lesion causes muscle atrophy (globe sinks back)

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12
Q

What is cranial nerve 6?

A

motor to lateral rectus and retractor bulbi
isolate lesion is rare
lesions cause
-medial globe deviation from LR
- inability to retract globe with RB

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13
Q

What is CN 7?

A

motor to muscles of facial expression
-close eyelids (obicularis oculi)
-ear position, lip move, nares move

carries parasymp fibers to lacrimal gland

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14
Q

What happens with a lesion at CN7

A

drooping superior lid (ptosis)
incomplete blink
decreased lacrimation
abnormalities of ear, lip, nares, position and movement

can be caused by otitis, hypothyroidism, trauma, etc

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15
Q

What is CN 8?

A

vestibular nerve

Afferent component of ocular position
controls EOM position so remain fixed on object while head turns
eyes can track smoothly
lesions cause eye drop/ nystagmus

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16
Q

What does cranial nerve 10 do?

A

Vagus
efferent arm of oculocardiac reflex
intaoperative handling of the eye causes brachycardia

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17
Q

What is the sympathetic pathway?

A

1st neuron=midbrain to T1-T3
2nd neuron= thorax
3rd= cranial cervical ganglion to eye

18
Q

What do sympathetic nerves innervate?

A

pupillary dilator muscle
smooth muscle in orbit and upper, lower, third eyelid

19
Q

What are the signs of horner’s syndrome?

A

ptosis (droopy lid)
enophthalmus ( sunken globe)
protrusion of nictitians
miosis (small pupil)
vasodilation of affected side
unilateral sweating

20
Q

What are ANS parasymp pupillary fibers and what do they do?

A

originate in PS nucleus of CN 3 (EWN)
travel with CN 3 to ciliary ganglion
enter globe as short ciliary nerves
act to constrict pupil
lesion causes dilated pupils

21
Q

What are ANS parasymp lacrimal gland fibers? What do they do?

A

efferent arm of lacrimation
fibers travel with CN 7
lesion= decreased tear production

Dry eye, dry nose, dilated pupil

22
Q

What are the parts of the vision pathway?

A

optical
photochemical
neurologic transmission/processing

23
Q

What is the optical path?

A

light
cornea
lens
retina
image is reversed and upside down on retina

24
Q

What is phototransduction?

A

cells convert photons of light to energy
occurs in photoreceptors

25
Q

What is signal transduction?

A

photoreceptors communicate with bipolar cells
amacrine cells
retinal ganglion cells
axons
optic nerve=sends signal to visual cortex for processing

26
Q

What is the track of the optic nerve?

A

axons convers and exit at optic disk
axons form optic nerve
medial axons of ON cross at optic chiasm
travel as optic tract to LGN

27
Q

What does crossing over of ON do?

A

integrates images from each eye

28
Q

How is the image reflexted on retina and ON/

A

If image is medial- optic nerve and retinal is lateral
vice versa
Lateral pathways cross over, medial do not
lateral is monocular, medial is binocular

29
Q

What is the meance response?

A

Afferent: retina and ON
Efferent CN7 and muscles of head
cover one eye, test medial and lateral visual fields
normal is blink

30
Q

What is the cottonball test?

A

throw cotton ball in air and then watch to see if head and eyes follow it

31
Q

Describe the steps in the vision pathway

A

retina/optic nerve
chiasm
optic tracts
lateral geniculate nucleus
optic radiations
visual cortex

32
Q

What is the afferent and efferent response of the pupillary light reflex?

A

A- retian and ON to chiasm to optic tract to pretectal nucleus and central decussation to EWN

E- parasymp fibers of EWN travel with CN 3 to spinchter

33
Q

Where does the PRL differ from the vision pathway?

A

At the level of the LGN

34
Q

What occurs if a lesion in the afferent arm of the PLR before LGN?

A

absent PLR and blindness

35
Q

What happens if there is a lesion from LGN to visual cortex

A

blind
still have normal PLR

36
Q

Waht happens if there is a lesion in the efferent PLR pathway?

A

not blind
abnormal PLR response

37
Q

What happens with a unilateral lesion of the optic nerve as an afferent deficit?

A

Side with lesion will not constrict and opposite side will not (no crossing over). Side without lesion will cause both eyes to constrict.
eye with lesion is blind

38
Q

What can cause afferent PLR deficits?

A

glaucoma
retinal detachment

39
Q

What happens to PLR with a unilateral efferent deficit

A

eye with lesion won’t constrict but opposite will.
if stim opposite eye, direct stimulation but affected eye doesn’t constrict

40
Q

What can cause efferent PLR deficits ?

A

Iris atrophy
posterior synechia
atropine

Healthy Animals Fall 22 (13 decks)

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